[Pg 484][40] The refining of silver in "tests" (Latin testa) is merely a second cupellation, with greater care and under stronger blast. Stirring the mass with an iron rod serves to raise the impurities which either volatilize as litharge or, floating to the edges, are absorbed into the "test." The capacity of the tests, from 15 librae to 50 librae, would be from about 155 to 515 ozs. Troy.
[Pg 487][41] A drachma of impurities in a bes, would be one part in 64, or 984.4 fine. A loss of a sicilicus of silver to the bes, would be one part in 32, or about 3.1%; three drachmae would equal 4.7%, and half an uncia 6.2%, or would indicate that the original bullion had a fineness in the various cases of about 950, 933, and 912.
[Pg 489][42] Praefectus Regis.
BOOK XI.
ifferent methods of parting gold from silver, and, on the other hand, silver from gold, were discussed in the last book; also the separation of copper from the latter, and further, of lead from gold as well as from silver; and, lastly, the methods for refining the two precious metals. Now I will speak of the methods by which silver must be separated from copper, and likewise from iron.[1]
